iOS: Psychology professors have made a new game, Personal Zen, can reduce anxiety in stressed individuals. All it takes is playing the free game for 25 minutes, according to research published in the journal Clinical Psychological Science.

Personal Zen is set in a garden where two faces—one happy and one angry—drop into the ground. The happy face creates a trail of grass that you have to quickly trace with your finger. Naturally, as you play more, your eyes get attuned to searching for the happy face instead of the angry one. All of this is backed up with a serene and calming background score, best played with earphones. Now here's the science of why it works:

The game is based on an emerging cognitive treatment for anxiety called attention-bias modification training (ABMT). Essentially, this treatment involves training patients to ignore a threatening stimulus (such as an angry face) and to focus instead on a non-threatening stimulus (such as a neutral or happy face). This type of training has been shown to reduce anxiety and stress among people suffering from high anxiety.

The researchers say that, at the moment, their findings suggest you need to play it for 25 minutes to reduce your anxiety, but they are testing to see if shorter periods of gameplay also have the same effect. Also note that this game works for normal stressed individuals, and it's unclear whether it will help those with clinically diagnosed anxiety.